public class test01 {
    class Solution {
        public int canCompleteCircuit(int[] gas, int[] cost) {
            int curSum = 0;
            int totalSum = 0;
            int index = 0;
            for(int i = 0;i<gas.length;i++){
                curSum += gas[i]-cost[i];
                totalSum += gas[i]-cost[i];
                if(curSum<0){
                    index = (i+1)%gas.length;
                    curSum = 0;
                }
            }
            if(totalSum<0){
                return -1;
            }
            return index;
        }
    }
}
